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There is a large number of diversion buffers inGNU M4, limited only by available memory. Text can be divertedinto any one of these buffers and then `undiverted' back to the output(diversion number 0) at a later stage.</P><P>Text is diverted and undiverted using the <CODE>divert</CODE> and<CODE>undivert</CODE> macros. They expand to the empty string, with the sideeffect of setting the diversion. Here is an illustrative example:</P><P><TABLE><tr><td> </td><td class=smallexample><FONT SIZE=-1><pre>divert(1)dnlThis goes at the end.divert(0)dnlThis goes at the beginning.undivert(1)dnl=>This goes at the beginning.=>This goes at the end.</FONT></pre></td></tr></table></P><P>It is unlikely that you will want to use diversions in your own macros,and it is difficult to do reliably without understanding the internalsof Autoconf. However, it is interesting to note that this is how<CODE>autoconf</CODE> generates fragments of shell code on-the-fly thatmust precede shell code at the current point in the <TT>`configure'</TT>script.</P><P><A NAME="Including files"></A></TR></TABLE><BR> <FONT SIZE="-1">This document was generatedby <I>Gary V. Vaughan</I> on <I>September, 12 2004</I>using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html"><I>texi2html</I></A></BODY></HTML>⌨️ 快捷键说明
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